The aorist active for [face=SPIonic]o(ra/w[/face] and for [face=SPIonic]ei)/dw [/face]is listed as [face=SPIonic]ei)=don[/face].
Looking at the stems I would think that [face=SPIonic]ei)=don[/face] belongs to [face=SPIonic]ei)/dw[/face].

I don't think [face=SPIonic]ei)/dw [/face]occurs in NT Greek so it makes sence that the Koine grammars list this form under [face=SPIonic]o(ra/w[/face] but why is it listed for [face=SPIonic]o(ra/w[/face] in Classical Greek also, instead of just leaving a blank?

hi bert, that's interesting, looking through lsj it looks like there isn't a present active [face=SPIonic]ei1dw[/face] (it's an assumed form, based on other tenses of the verb).

the aorist 2 of that "assumed" verb serves as aorist to [face=SPIonic]o(ra&w[/face].

so the verbs are locked together. if they left it blank that might not be obvious, and in particular it'd make greek composition harder, if you were trying to track down the aorist of [face=SPIonic]o(ra&w[/face].